The proposed experiments study the process by which differences in mothers' responsiveness to infant signals are created. It is proposed that differences in signal detection (sensitivity or response bias) provide a mechanism for how maternal responsiveness is molded by experience, beliefs, and expectations. The experiments share the use of signal detection methodology (Statistical Decision Theory (Green & Swets, 1966; Macmillan & Creelman, 1991) to examine the independent aspects of sensory sensitivity and response bias in the formulation of maternal response. The aim is to measure sources of variation in maternal sensitivity/responsiveness to infant signals and to link such variations to a developmental outcome that involves a strong affective component - infant-mother attachment. Experiments I and II are linked conceptually in that both seek to determine the effects of extended experience with negative emotionality of the infant, such as distress, fear, or anger, which may be expressed through infant crying. Experiment I is designed to determine whether experience with failure and learning of one's ineffectiveness leads to reduced maternal responsiveness through changes in the sensory system or in the response choice system. Experiment III likewise explores the effects of extended experience with infant negative emotionality. Negative emotionality is central to the definition of difficult temperament, together with unreliability and difficulty in being soothed. In Expedient III, experience with infant difficulty is experimentally induced to determine the effects on subsequent processing of infants signals. The frequency with which mothers experience cry termination serves to "mirror" infant temperament differences. High and low frequency termination will represent "easy" and "difficult" infants, respectively. The research will determine whether the sensory or the response choice system effected by such a manipulation. Experiment II is designed to examine the contribution of sensory sensitivity to maternal sensitivity measured under different conditions to validate the laboratory procedure. The predictive power of both sensory and behavioral sensitivity for one specific developmental outcome where the role of affect is central, infant-mother attachment, will be assessed. At issue is the degree to which maternal sensitivity early in infancy predicts the quality of social interaction and helps establish a continuity in infants' affective signaling. Experminet IV will experimentally manipulate an infant characteristic known to affect maternal responsiveness - infant gender. Infant gender will be manipulated through "labeling." The use of the signal detection paradigm allows examination of the difference between sensory processing and response bias in the formulation of mothers' responses to infant affective signaling under the two conditions.